Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
  • B32B27/327—Layered products comprising a layer of synthetic resin comprising polyolefins comprising polyolefins obtained by a metallocene or single-site catalyst
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/06—Polyethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/16—Elastomeric ethene-propene or ethene-propene-diene copolymers, e.g. EPR and EPDM rubbers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2323/00—Polyalkenes
  • B32B2323/04—Polyethylene
  • B32B2323/046—LDPE, i.e. low density polyethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
  • B32B2439/70—Food packaging
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2314/00—Polymer mixtures characterised by way of preparation
  • C08L2314/06—Metallocene or single site catalysts
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31678—Of metal
  • Y10T428/31692—Next to addition polymer from unsaturated monomers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31725—Of polyamide
  • Y10T428/31739—Nylon type
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31725—Of polyamide
  • Y10T428/31739—Nylon type
  • Y10T428/31743—Next to addition polymer from unsaturated monomer[s]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31786—Of polyester [e.g., alkyd, etc.]
  • Y10T428/31797—Next to addition polymer from unsaturated monomers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/31909—Next to second addition polymer from unsaturated monomers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31971—Of carbohydrate
  • Y10T428/31993—Of paper

Definitions

• the present invention relates to a laminate. More particularly, the invention relates to a laminate having a layer made of a polyethylene composition and having an excellent balance among tearability, punchability, heat-sealing strength, low-temperature heat sealability, and hot-tack properties.
• Laminates which have been used as the materials of conventional packages/containers are ones obtained by laminating a polyethylene resin comprising high-pressure-process low-density polyethylene (LDPE), an ethylene/vinyl acetate copolymer (EVA), or the like as a heat-sealable layer resin to a base such as paper or a biaxially oriented polyamide, polyester, polypropylene, or the like, from the standpoint of imparting properties required of containers having heat sealability, moisture-proof properties, etc.
• LDPE high-pressure-process low-density polyethylene
• EVA ethylene/vinyl acetate copolymer
• LLDPE linear low-density polyethylene
• the LLDPE produced by polymerization with a metallocene catalyst is characterized by being heat-sealable at low temperatures and having high sealing strength and high hot-tack strength, and is in extensive use as a sealant in light packages, paper containers for liquids, etc.
• the polyethylene has problems, for example, that it shows poor punchabili ty and cannot be punched and the resin layer stretches disadvantageously, resulting in a poor appearance.
• the polyethylene When used in binding paper or easy-to-tear packages, the polyethylene has problems, for example, that since it has poor tearability, opening necessitates power and the resin layer stretches. Many attempts have been made to overcome those problems.
• an object of the invention is to provide a laminate which is satisfactory in tearability, punchability, low-temperature heat sealability, heat-sealing strength, and hot-tack properties and is excellent in ease of opening, punchability, and contents-protecting performance.
• a laminate comprising a layer of a polyethylene composition comprising a specific ethylene-based terpolymer and a specific low-density polyethylene (referred to also as a polyethylene composition layer) and a base layer can be a laminate which is satisfactory in tearability, punchability, heat sealability, heat-sealing strength, and hot-tack properties and is excellent in ease of opening, punchability, and contents-protecting performance.
• the invention has been thus completed, which has the constitutions shown below.
• the laminate of the invention is a laminate satisfactory in tearability, punchability, heat-sealing strength, low-temperature heat sealability, and hot-tack properties and excellent in ease of opening, punchability, and contents-protecting performance, because it comprising a polyethylene composition layer comprising a specific ethylene-based terpolymer and a specific low-density polyethylene and a base layer.
• the invention is a laminate comprising: a polyethylene composition layer comprising an ethylene-based terpolymer (A) which has the following properties (a-1) to (a-4) and optionally further has the property (a-5) and a low-density polyethylene (B) obtained by the high-pressure radical polymerization method which has the following properties (b-1) to (b-3); and a base layer.
• A ethylene-based terpolymer
• a-5 ethylene-based terpolymer
• B low-density polyethylene
• the ethylene-based terpolymer (A) to be used in the polyethylene composition layer in the invention is a terpolymer of ethylene, propylene, and either 1-hexene or 1-octene and has the following properties (a-1) to (a-4). It further has the following property (a-5) according to need.
• the melt flow rate (MFR: 190°C, 21.18-N load) of the ethylene-based terpolymer to be used in the invention is 0.1-100 g/10 min, preferably 1-60 g/10 min, more preferably 5-50 g/10 min. MFR's lower than 0.1 g/10 min are undesirable because the polyethylene composition has poor spreadability during molding and an increased load is imposed on the motor in the extruder. On the other hand, MFR's exceeding 100 g/10 min are undesirable because the melt film during molding is in an unstable state.
• MFR for regulating the MFR of the ethylene-based terpolymer, use may be made of a method in which the polymerization temperature, catalyst amount, feed amount of hydrogen as a molecular weight regulator, etc. are suitably regulated.
• the values of MFR herein are ones measured in accordance with JIS-K7210 (190°C, 21.18-N load).
• the density of the ethylene-based terpolymer to be used in the invention is 0.87-0.92 g/cm 3 , preferably 0.88-0.915 g/cm 3 , more preferably 0.89-0.91 g/cm 3 .
• Densities lower than 0 . 870 g/cm 3 are undesirable because the polyethylene composition layer has poor unsusceptibility to blocking.
• densities exceeding 0.92 g/cm 3 are undesirable because the polyethylene composition layer has poor low-temperature heat sealability.
• the values of density herein are ones determined in accordance with JIS K7112.
• the ethylene-based terpolymer to be used in the invention is one obtained by copolymerizing ethylene as the main ingredient with propylene and either 1-hexene or 1-octene.
• the ethylene content in the terpolymer is 80-99% by mole, preferably 83-98% by mole, more preferably 85-97% by mole.
• Ethylene contents lower than 80% by mole are undesirable because the polyethylene composition layer has poor unsusceptibility to blocking.
• Ethylene contents exceeding 99% by mole are undesirable because the polyethylene composition layer has poor low-temperature heat sealability.
• the values of ethylene content herein are ones determined by 13 C-NMR spectroscopy.
• the ratio of the molar proportion of propylene (Mp) to the molar proportion of 1-hexene or 1-octene (Mh), Mp/Mh is 1.5 or higher, preferably 1.8-6.5, more preferably 2.0-5.5. Mp/Mh ratios lower than 1.5 are undesirable because the polyethylene composition layer has poor tearability, resulting in impaired suitability for opening.
• the values of the molar proportion of propylene (Mp) and the molar proportion of 1-hexene or 1-octene (Mh) herein are ones determined by the 13 C-NMR spectroscopy described in Macromolecules, (1982) 15, pp.1150-1152 under the following conditions.
• Apparatus Unity Plus 400, manufactured by Varian Inc. Solvent: o-dichlorobenzene (75)/benzene-d6 (25) Examination concentration: 15 (wt/v)% Examination temperature: 120°C Pulse sequence: 1H complete decoupling method Pulse angle: 90° Pulse duration: 20 seconds
• the density (d) (g/cm 3 ) and melting point (Tm) (°C) of the ethylene-based terpolymer to be used in the invention preferably satisfy expression (1).
• 1220 ⁇ d - 1019 ⁇ Tm ⁇ 1220 ⁇ d - 1005 (In expression (1), the melting point (Tm) is a melting point as measured during second scanning with a DSC in accordance with JIS K7121, the melting point corresponding to the maximum peak height.) They more preferably satisfy expression (1').
• the melting point (Tm) is a melting point as measured during second scanning with a DSC, the melting point corresponding to the maximum peak height.
• expressions (1) and (1') are expressions derived from the results of many experiments and are indexes to the width of crystalline distribution. When the ethylene-based terpolymer satisfies either of those expressions, this means that the terpolymer has a narrow crystalline distribution. In case where Tm is outside the upper limit, the polyethylene composition layer has poor tearability. In case where Tm is outside the lower limit, the polyethylene compositionlayer haspoorlow-temperaturehot-tackproperties.
• Processes for producing the ethylene-based terpolymer to be used in the invention are not particularly limited with respect to the catalyst and polymerization method to be used, as long as a copolymer having the properties (a-1) to (a-4) described above and optionally further having the property (a-5) can be produced.
• examples of catalysts suitable for producing a polymer such as the terpolymer described above include metallocene catalysts.
• the metallocene catalysts include the catalysts comprising a metallocene compound and a cocatalyst and optionally further including an organoaluminum compound which are described in, e.g., JP-A-58-19309 , JP-A-59-95292 , JP-A-60-35006 , JP-A-60-35007 , JP-A-60-35008 , JP-A-61-130314 , JP-A-3-163088 , European Patent Application Publication No. 420, 436 , U.S. Patent No. 5,055,438 , International Publication WO 91/04257 , and International Publication WO 92/07123 .
• metallocene compound examples include bis(cyclopentadienyl) zirconium dichloride, bis(indenyl)zirconium dichloride, bis(fluorenyl)zirconium dichloride, bis(azulenyl)zirconium dichloride, bis(4,5,6,7-tetrahydroindenyl)zirconzum dichloride, (cyclopentadienyl) (3, 4-dimethylcyclopentadienyl) zirconium dichloride, methylenebis(cyclopentadienyl)zirconium dichloride, methylene(cyclopentadienyl)(3,4-dimethylcyclopentadienyl)zirconium dichloride, isopropylidene(cyclopentadienyl)(3,4-dimethylcyclopentadien yl)zirconium dichloride, ethylene(cyclopentadienyl)(3,5-dimethylp
• the cocatalyst to be used in combination with the metallocene compound means a substance which enables the metallocene compound to effectively function as a polymerization catalyst or which can balance ionic charges in a catalytically activated state.
• the cocatalyst to be used in the invention include organoaluminumoxy compounds such as benzene-soluble aluminoxanes and benzene-insoluble organoaluminumoxy compounds, ion-exchange phyllosilicates, boron compounds, lanthanoid salts such as lanthanum oxide, and tin oxide.
• the metallocene compound may be used after having been deposited on a support comprising an inorganic or organic compound.
• the support preferably is a porous oxide of an inorganic or organic compound. Examples thereof include ion-exchange phyllosilicates, SiO 2 , Al 2 O 3 , MgO, ZrO 2 , TiO 2 , B 2 O 3 , CaO, ZnO, BaO, ThO 2 , and mixtures thereof.
• trialkylaluminums such as triethylaluminum, triisopropylaluminum, and triisobutylaluminum
• dialkylaluminum halides alkylaluminum sesquihalides
• alkyl aluminum dihalides alkyl aluminum halides
• organoaluminum alkoxides organoaluminum alkoxides.
• Examples of polymerization methods for producing the terpolymer of ethylene, propylene, and 1-hexene or 1-octene using the catalyst described above include the vapor-phase polymerization method, solution polymerization method, and high-pressure polymerization method.
• the vapor-phase polymerization method it is preferred to conduct polymerization at a reaction temperature of about 50-100°C and a reaction pressure of about 10-40 kgf/cm 2 .
• the solution polymerization method it is preferred to conduct polymerization at a reaction temperature of about 100-300°C and a reaction pressure of about 10-60 kgf/cm 2 using cyclohexane as a solvent.
• the high-pressure polymerization method it is preferred to conduct polymerization at a reaction temperature of about 150-300°C and a reaction pressure of about 200-1,500 kgf/cm 2 .
• the low-density polyethylene (B) to be used in the polyethylene composition layer in the invention is a low-density polyethylene (preferably, long-chain branched low-density polyethylene) which has been produced by the high-pressure radical polymerization method and has the following properties (b-1) to (b-3).
• the melt flow rate (MFR) of the low-density polyethylene to be used in the invention is 0.1-20 g/10 min, preferably 1-15 g/10 min, more preferably 2-15 g/10 min.
• MFR melt flow rate
• the MFR thereof is lower than 0.1 g/10 min, the polyethylene composition has insufficient spreadability and suffers film breakage during high-speed molding.
• the MFR thereof exceeds 20 g/10 min, the melt film becomes unstable.
• the values of MFR herein are ones measured in accordance with JIS-K7210 (190°C, 21.18-N load).
• the density of the low-density polyethylene to be used in the invention is 0.915-0.93 g/cm 3 , preferably 0.916-0.926 g/cm 3 , more preferably 0.917-0.925 g/cm 3 .
• the density thereof is lower than 0.915 g/cm 3
• the polyethylene composition layer has enhanced tackiness.
• densities thereof exceeding 0.93 g/cm 3 result in poor low-temperature heat sealability.
• the values of density herein are ones determined in accordance with JIS K7112.
• the memory effect (ME) of the low-density polyethylene to be used in the invention is 1. 6 or higher, preferably 1.8-3, more preferably 1 . 9-2 . 6 . In case where the memory effect thereof is lower than 1.6, the melt film is unstable.
• the low-density polyethylene to be used in the invention is produced generally by polymerizing ethylene using a tank type reactor or a tubular reactor in the presence of a radical generator under the conditions of a polymerization pressure of 1,400-3,000 kg/cm 2 and a polymerization temperature of 200-300°C.
• the melt flow rate thereof can be regulated by using hydrogen or a hydrocarbon, such as methane or ethane, as a molecular weight regulator.
• the proportion of the ethylene-based terpolymer (A) to the low-density polyethylene (B) produced by the high-pressure radical polymerization method is (10-95% by weight):(5-90% by weight), preferably (20-90% by weight):(10-80% by weight), more preferably (30-85% by weight) : (15-70% by weight).
• the proportion of the ethylene-based terpolymer is too large, the melt film has poor stability.
• the proportion of the low-density polyethylene produced by the high-pressure radical polymerization method is too large,the polyethylene composition layer has reduced heat-sealing strength.
• Additives in common use in polyethylene resins such as antioxidants, e.g., phenolic compounds and phosphorus compounds, stabilizers, e.g., metal soaps, antiblocking agents, lubricants, dispersants, pigments, e.g., organic or inorganic colorants, antifogging agents, e.g., unsaturated fatty acid esters, antistatic agents, ultraviolet absorbers, light stabilizers, and nucleating agents, may be incorporated according to need into the polyethylene composition layer to be used in the invention.
• antioxidants e.g., phenolic compounds and phosphorus compounds
• stabilizers e.g., metal soaps
• antiblocking agents e.g., lubricants, dispersants
• pigments e.g., organic or inorganic colorants
• antifogging agents e.g., unsaturated fatty acid esters, antistatic agents, ultraviolet absorbers, light stabilizers, and nucleating agents
• thermoplastic resins such as polyethylene resins, e.g., LDPE, C4-LLDPE, HAO-LLDPE, ethylene/vinyl acetate copolymers (EVA), ethylene/acrylic acid copolymers (EAA), ethylene/methacrylic acid copolymers (EMAA), ethylene/acrylic ester copolymers (EEA, EMA, EMMA, etc.), and high-density polyethylene (HDPE), adhesive resins, e.g., ethylene/maleic anhydride copolymers, polypropylene resins, and polystyrene resins may be incorporated as long as this incorporation does not impair the properties of the polyethylene composition layer.
• adhesive resins e.g., ethylene/maleic anhydride copolymers, polypropylene resins, and polystyrene resins may be incorporated as long as this incorporation does not impair the properties of the polyethylene composition layer.
• Examples of the base layer to be used in the invention include single-layer films of a nylon, polyester, polyropylene, polyethylene, ethylene/vinyl alcohol copolymer, or the like or multilayer films made of the same or different materials selected from these. These films preferably are stretched films.
• Examples of the base layer further include single-layer bases or multilayer bases such as papers, e.g., kraft paper, foils of a metal, e.g., aluminum or copper, and plastic films coated with a metal or an inorganic or organic substance by vapor deposition.
• the laminate of the invention is a laminate comprising a base layer and a polyethylene composition layer formed on at least one side thereof.
• Processes for producing the laminate are not particularly limited.
• theso-calledextrusion coating method is preferably in which the polyethylene composition is melt-extruded and superposed on abase layer .
• the extrusion coating it is preferred to superpose one or more layers by a method such as single-layer extrusion, sandwich laminating, coextrusion laminating, or tandem laminating.
• the polyethylene composition layer can be used not only as a surface-layer sealant but also as an adhesive layer. According to the invention, a melt film is stably extruded and, hence, high-speed molding is possible.
• Methods for securing adhesion to the base layer are not particularly limited.
• a surface of the base it is preferred to subject a surface of the base to a surface treatment or an anchor coating treatment.
• techniques for the surface treatment include various treatment techniques such as corona discharge treatment, ozone treatment, flame treatment, and low-temperature plasma treatment. Examples thereof further include a method in which ozone is blown against the molten resin.
• the laminate of the invention is formed using the ethylene-based terpolymer described above. It is a laminate satisfactory in tearability, punchability, heat-sealing strength, low-temperature heat sealability, and hot-tack properties and excellent in ease of opening and contents-protecting performance.
• the laminate of the invention is excellent in tearability, punchability, heat-sealing strength, low-temperature heat sealability, and hot-tack properties, it can be used as a film for easy-to-tear package bags, film for food packaging, paper container for liquids, binding paper, paper cups, paper trays, etc.
• Methyl aluminoxane manufactured by Toyo Stauffer was added to 2.0 mmol of ethylenebis(4,5,6,7-tetrahydroindenyl)zirconium dichloride, which is a complex, in an amount 1, 000 times by mole the amount of the complex.
• This mixture was diluted with toluene to adjust the volume to 10 L.
• a catalyst solution was prepared. This catalyst solution was introduced into a stirring autoclave type continuous reactor having a capacity of 1.5 L.
• PE-1 ethylene/propylene/1-hexene terpolymer
• T-180 manufactured by Mitsubishi Polyester Film Corp.
• Example 2 Molding and evaluation were conducted in the same manner as in Example 1, except that long-chain branched low-density polyethylene produced by the high-pressure radical polymerization method having an MFR of 8 g/10 min, density of 0.918 g/cm 3 , and ME of 2.2 (LDPE-2) was used in Example 1 as a low-density polyethylene in an amount of 40% by weight.
• the evaluation results are shown in Table 2.
• Example 2 Molding and evaluation were conducted in the same manner as in Example 1, except that LDPE-2 was used in Example 2 in an amount of 60% by weight. The evaluation results are shown in Table 2.
• Example 2 Molding and evaluation were conducted in the same manner as in Example 1, except that PE-5 and LDPE-2 were used in Example 1 as an ethylene-based terpolymer and a long-chain branched low-density polyethylene produced by the high-pressure radical polymerization method, respectively.
• the evaluation results are shown in Table 2.
• Example 2 Molding and evaluation were conducted in the same manner as in Example 1, except that the ethylene-based terpolymer was not used in Example 2. The evaluation results are shown in Table 2.
• Example 2 Molding and evaluation were conducted in the same manner as in Example 1, except that the LDPE was not used in Example 1. The evaluation results are shown in Table 2.
• Example 2 Molding and evaluation were conducted in the same manner as in Example 1, except that PE-7 and LDPE-2 were used in Example 1 as an ethylene-based terpolymer and a long-chain branched low-density polyethylene produced by the high-pressure radical polymerization method, respectively.
• the evaluation results are shown in Table 2.
• the laminates of the invention have a high heat-sealing strength and, despite this, have a low tear strength. Consequently, they are laminates having an excellent balance between heat-sealing strength and tearability.
• the polyethylene-based films obtained using either an ethylene terpolymer having an Mp/Mh lower than 1.5 or an ethylene/1-hexene bipolymer have poor tearability (Comparative Examples 3, 4, and 5), while the polyethylene-based film obtained using no terpolymer has a poor balance between impact strength and tearability (Comparative Example 1).
• the polyethylene composition containing a low-density polyethylene having a low ME gives an unstable melt film (Comparative Example 6) .
• a polyethylene composition composed of 60% by weight PE-1 as an ethylene-based terpolymer and 40% by weight long-chain branched low-density polyethylene having an MFR of 4 g/10 min, density of 0.918 g/cm 3 , and ME of 2.4 (LDPE-1) was granulated with a 40-mm single-screw extruder.
• pellets of the polyethylene composition were obtained.
• the pellets obtained were extruded through a die having a width of 360 mm at a molding temperature of 320°C so as to result in a film thickness of 20 ⁇ m onto 75-g/m 2 kraft paper.
• the base was subjected to an in-line corona treatment. The results of evaluation of the laminate are shown in Table 3.
• the laminate of the invention has a high heat-sealing strength and, despite this, has a low tear strength. Consequently, it is a laminate having an excellent balance between heat-sealing strength and tearability.
• the polyethylene-based film obtained using no terpolymer has a poor balance between impact strength and tearability (Comparative Example 8).
• the polyethylene-based film obtained using an ethylene/1-hexene copolymer has poor tearability (Comparative Example 9).
• the laminate of the invention can be used as a film for easy-to-tear package bags, film for food packaging, paper container for liquids, binding paper, paper cups, paper trays, etc. While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. This application is based on a Japanese patent application filed on August 17, 2004 (Application No. 2004-237365 ), the contents thereof being herein incorporated by reference.

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• 2005
  • 2005-08-15 WO PCT/JP2005/014897 patent/WO2006019066A1/fr active Application Filing
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